Scaling of base Shear

[ahmedhegazi]

Hi all
In case we builing that consist of 5 Basement and 25 Floors over ground, should scaling for respobse spectrum be carried out at base level or at ground floor level?

 

[prsconsultant]

Take a look at the static story shear distribution at each floor. Watchout for the force reversals. I typically comeup with the scaling factor based on the nearest floor to the floor where the force reversal is happening. If there are no reversals use the shears at the first floor above grade for scaling.